@article {543, title = {Intragenus (Campylomormyrus) and intergenus hybrids in mormyrid fish: physiological and histological investigations of the electric organ ontogeny}, journal = {Journal of Physiology-Paris}, year = {2017}, month = {Jan-01-2017}, abstract = {

African weakly electric mormyrid fish show a high diversity of their electric organ discharge (EOD) both across and within genera. Thanks to a recently developed technique of artificial reproduction in mormyrid fish, we were able to perform hybridizations between different genera and within one genus (Campylomormyrus). The hybrids of intergenus hybridizations exhibited different degrees of reduced survival related to the phylogenetic distance of the parent species: hybrids of the crosses between C. rhynchophorus and its sister genus Gnathonemus survived and developed normally. Hybrids between C. rhynchophorus and a Mormyrus species (a more basal clade compared to Campylomormyrus s) survived up to 42 days and developed many malformations, e.g., at the level of the unpaired fins. Hybrids between C. numenius and Hippopotamyrus pictus (a derived clade, only distantly related to Campylomormyrus) only survived for two days during embryological development. Seven different hybrid combinations among five Campylomormyrus species (C. tamandua, C. compressirostris, C. tshokwe, C. rhynchophorus, C. numenius) were performed. The aim of the hybridizations was to combine species with (1) either caudal or rostral position of the main stalk innervating the electrocytes in the electric organ and (2) short, median or long duration of their EOD. The hybrids, though they are still juveniles, show very interesting features concerning electrocyte geometry as well as EOD form and duration: the caudal position of the stalk is prevailing over the rostral position, and the penetration of the stalk is dominant over the non-penetrating feature (in the Campylomormyrus hybrids); in the hybrid between C. rhynchophorus and Gnathonemus petersii it is the opposite. When crossing species with long and short EODs, it is always the long duration EOD that is expressed in the hybrids. The F1-Hybrids of the cross C. tamandua x C. compressirostris are fertile: viable F2-fish could be obtained with artificial reproduction

}, keywords = {Artificial reproduction, Campylomormyrus, Electric organ ontogeny, Hybrids, mormyrids}, issn = {09284257}, doi = {10.1016/j.jphysparis.2017.01.003}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0928425717300037}, author = {Frank Kirschbaum and Nguyen, Linh and Baumgartner, Stephanie and Chi, Linda and Wolfart, Rene and Elarbani, Khouloud and Eppenstein, Hari and Korniienko, Yevheniia and Guido-B{\"o}hm, Lilian and Victor Mamonekene and Vater, Marianne and Ralph Tiedemann} } @article {536, title = {Evidence for Non-neutral Evolution in a Sodium Channel Gene in African Weakly Electric Fish (Campylomormyrus, Mormyridae)}, journal = {Journal of Molecular Evolution}, year = {2016}, month = {Jan-08-2016}, pages = {1{\textendash}17}, abstract = {

Voltage-gated sodium channels, Nav1, play a crucial role in the generation and propagation of action potentials and substantially contribute to the shape of their rising phase. The electric organ discharge (EOD) of African weakly electric fish (Mormyroidea) is the sum of action potentials fired from all electrocytes of the electric organ at the same time and hence voltage-gated sodium channels are one factor\—together with the electrocyte\’s morphology and innervation pattern\—that determines the properties of these EODs. Due to the fish-specific genome duplication, teleost fish possess eight copies of sodium channel genes (SCN), which encode for Nav1 channels. In mormyroids, SCN4aa is solely expressed in the electrocytes of the adult electric organ. In this study, we compared entire SCN4aa sequences of six species of the genus Campylomormyrus and identified nonsynonymous substitutions among them. SCN4aa in Campylomormyrus exhibits a much higher evolutionary rate compared to its paralog SCN4ab, whose expression is not restricted to the electric organ. We also found evidence for strong positive selection on the SCN4aa gene within Mormyridae and along the lineage ancestral to the Mormyridae. We have identified sites at which all nonelectric teleosts are monomorphic in their amino acid, but mormyrids have different amino acids. Our findings confirm the crucial role of SCN4aa in EOD evolution among mormyrid weakly electric fish. The inferred positive selection within Mormyridae makes this gene a prime candidate for further investigation of the divergent evolution of pulse-type EODs among closely related species.

}, issn = {0022-2844}, doi = {10.1007/s00239-016-9754-8}, url = {http://link.springer.com/10.1007/s00239-016-9754-8}, author = {Paul, Christiane and Frank Kirschbaum and Victor Mamonekene and Ralph Tiedemann} } @article {499, title = {Species delimitation and phylogenetic relationships in a genus of African weakly-electric fishes (Osteoglossiformes, Mormyridae, Campylomormyrus)}, journal = {Molecular Phylogenetics and Evolution}, year = {2016}, month = {Jan-04-2016}, abstract = {

African weakly-electric fishes (Mormyridae) are able to communicate through species-specific electric signals; this feature might have favoured the evolutionary radiation observed in this family (over 200 species) by acting as an effective pre-zygotic isolation mechanism. In the present study we used mitochondrial (cytb) and nuclear (rps7, scn4aa) markers in order to reconstruct a species-phylogeny and identify species boundaries for the genus Campylomormyrus, by applying inference methods based on the multispecies coalescent model. Additionally, we employed 16 microsatellite markers, landmark-based morphometric measurements, and electro-physiological analyses as independent lines of evidence to the results obtained from the sequence data. The results show that groups that are morphologically different are also significantly divergent at the genetic level, whereas morphologically similar groups, displaying dissimilar electric signals, do not show enough genetic diversity to be considered separate species. Furthermore, the data confirm the presence of a yet undescribed species within the genus Campylomormyrus.

}, keywords = {Campylomormyrus, Geometric morphometrics, Microsatellites, Mormyridae, Multispecies-coalescent, Species-delimitation}, issn = {10557903}, doi = {10.1016/j.ympev.2016.04.035}, url = {http://linkinghub.elsevier.com/retrieve/pii/S1055790316300781}, author = {Lamanna, Francesco and Frank Kirschbaum and Ernst, Anja R.R. and Philine G.D. Feulner and Victor Mamonekene and Paul, Christiane and Ralph Tiedemann} } @article {480, title = {Comparative histology of the adult electric organ among four species of the genus Campylomormyrus (Teleostei: Mormyridae)}, journal = {Journal of Comparative Physiology A}, volume = {201}, year = {2015}, month = {Jan-04-2015}, pages = {357 - 374}, abstract = {

The electric organ (EO) of weakly electric mormyrids consists of flat, disk-shaped electrocytes with distinct anterior and posterior faces. There are multiple species-characteristic patterns in the geometry of the electrocytes and their innervation. To further correlate electric organ discharge (EOD) with EO anatomy, we examined four species of the mormyrid genus Campylomormyrus possessing clearly distinct EODs. In C. compressirostris, C. numenius, and C. tshokwe, all of which display biphasic EODs, the posterior face of the electrocytes forms evaginations merging to a stalk system receiving the innervation. In C. tamandua that emits a triphasic EOD, the small stalks of the electrocyte penetrate the electrocyte anteriorly before merging on the anterior side to receive the innervation. Additional differences in electrocyte anatomy among the former three species with the same EO geometry could be associated with further characteristics of their EODs. Furthermore, in C. numenius, ontogenetic changes in EO anatomy correlate with profound changes in the EOD. In the juvenile the anterior face of the electrocyte is smooth, whereas in the adult it exhibits pronounced surface foldings. This anatomical difference, together with disparities in the degree of stalk furcation, probably contributes to the about 12 times longer EOD in the adult.

}, issn = {0340-7594}, doi = {10.1007/s00359-015-0995-6}, url = {http://link.springer.com/10.1007/s00359-015-0995-6}, author = {Paul, Christiane and Victor Mamonekene and Vater, Marianne and Philine G.D. Feulner and Engelmann, Jacob and Ralph Tiedemann and Frank Kirschbaum} } @article {167, title = {Electrophysiological and molecular genetic evidence for sympatrically occuring cryptic species in African weakly electric fishes (Teleostei: Mormyridae: Campylomormyrus)}, journal = {Biology Letters Evolutionary Biology}, volume = {39}, year = {2006}, pages = {198-208}, abstract = {

For two sympatric species of African weakly electric Wsh, Campylomormyrus tamandua and Campylomormyrus numenius, we moni- tored ontogenetic diVerentiation in electric organ discharge (EOD) and established a molecular phylogeny, based on 2222 bp from cyto- chrome b, the S7 ribosomal protein gene, and four Xanking regions of unlinked microsatellite loci. In C. tamandua, there is one common EOD type, regardless of age and sex, whereas in C. numenius we were able to identify three diVerent male adult EOD waveform types, which emerged from a single common EOD observed in juveniles. Two of these EOD types formed well supported clades in our phyloge- netic analysis. In an independent line of evidence, we were able to aYrm the classiWcation into three groups by microsatellite data. The correct assignment and the high pairwise FST values support our hypothesis that these groups are reproductively isolated. We propose that in C. numenius there are cryptic species, hidden behind similar and, at least as juveniles, identical morphs.

}, doi = {10.1016/j.ympev.2005.09.008}, author = {Philine G.D. Feulner and Frank Kirschbaum and Victor Mamonekene and Ketmaier, V. and Ralph Tiedemann} } @article {889, title = {Adaptive radiation in African weakly electric fish (Teleostei: Mormyridae: Campylomormyrus): a combined molecular and morphological approach}, journal = {Journal of Evolutionary Biology}, volume = {20}, year = {2007}, month = {01/2007}, pages = {403 - 414}, abstract = {

We combined multiple molecular markers and geometric morphometrics to revise the current taxonomy and to build a phylogenetic hypothesis for the African weakly electric fish genus Campylomormyrus. Genetic data (2039 bp DNA sequence of mitochondrial cytochrome b and nuclear S7 genes) on 106 specimens support the existence of at least six species occurring in sympatry. We were able to further confirm these species by microsatellite analysis at 16 unlinked nuclear loci and landmark-based morphometrics. We assigned them to nominal taxa by comparisons to type specimens of all Campylomormyrus species recognized so far. Additionally, we showed that the shape of the elongated trunk-like snout is the major source of morphological differentiation among them. This finding suggests that the radiation of this speciose genus might have been driven by adaptation to different food sources.

}, issn = {1420-9101}, doi = {10.1111/j.1420-9101.2006.01181.x}, author = {Philine G.D. Feulner and Frank Kirschbaum and Victor Mamonekene and Ketmaier, V. and Ralph Tiedemann} }